HIGH VELOCITY AIR FILTERS
A study was made of the performance of fibrous filters with the specific objective of obtaining design information for high-velocity air filters. Experimental data on pressure drop, collection efficiency, and life for fibrous filters were obtained with two supercooled liquid aerosols (0.3 and 1.4 microns diameter) and one solid aerosol (1.2 micron diameter). Filter fiber size ranged from 3 to 30 microns, filter pad density from 0.01 to 0.10 cu. ft fiber/cu. ft pad, and filter velocity from 0.3 to 100 ft/sec. The data on the collection of liquid aerosols agreed well with theoretical predictions. Collection efficiencies with the solid aerosol particles were very much lower, however, at filtration velocities over 1 ft/sec, apparently due to failure of all colliding particles to adhere to the fibers. The density or degree of compaction of the aerosol deposit was a controlling factor in determining the manner in which aerosol loading of the filter affected pressure drop and collection efficiency. The degree of compaction was, in turn, dependent on both the characteristics of the aerosol particles and on the operating conditions. In the case of the solid aerosol, vibration of the filter produces major effects only at frequencies over 1200 cycles/sec, which was beyond the designed capacity of the vibration equipment. High filter velocities, however, resulted in marked dislodgment and internal redeposition and compaction of previously collected solid aerosol. Data are also presented on pressure drop and collection efficiency for pad-supporting screens, on the mechanical compressibility characteristics of fibers, and on two novel arrangements for particle size analysis. (auth)
- Research Organization:
- Donaldson Co., Inc., St. Paul
- NSA Number:
- NSA-13-009118
- OSTI ID:
- 4291592
- Report Number(s):
- WADC-TR-55-457; AD-142075
- Country of Publication:
- United States
- Language:
- English
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